Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Qual sistema possui uma versão atual 9.0?
 ###Tabelas: CREATE TABLE league (league_id AUTO_INCREMENT PRIMARY KEY, Team VARCHAR, City VARCHAR, Inaugural season VARCHAR, Final season VARCHAR, Captain VARCHAR, Coach VARCHAR) CREATE TABLE  (_id AUTO_INCREMENT PRIMARY KEY, Name VARCHAR, Actual version VARCHAR, System VARCHAR, Platform VARCHAR, License VARCHAR) CREATE TABLE former_judges (former_judges_id AUTO_INCREMENT PRIMARY KEY, State VARCHAR, Born/Died VARCHAR, Active service VARCHAR, Chief Judge VARCHAR, Senior status VARCHAR, Appointed by VARCHAR, Reason for termination VARCHAR) CREATE TABLE 1980–1989 (1980–1989_id AUTO_INCREMENT PRIMARY KEY, January VARCHAR, February VARCHAR, March VARCHAR, April VARCHAR, June VARCHAR, July VARCHAR, August VARCHAR, September VARCHAR, October VARCHAR, November VARCHAR, December VARCHAR) CREATE TABLE linebackers (linebackers_id AUTO_INCREMENT PRIMARY KEY, Position VARCHAR, Player VARCHAR, Period VARCHAR, Teams VARCHAR, Consecutive starts INT, Playoffs INT, Total INT)  
SELECT System FROM  WHERE Actual version = 9.0